CHECK PHP SESSION - ISSET($SESSION

Check PHP Session: isset($_SESSION) Is Not Working

It sounds like you are having an issue with the isset() function in PHP not working properly when checking for a session variable. Here are a few things to check:

Make sure that the session has been started with the session_start() function at the very top of your script, before any HTML or whitespace output.
Check that you are using the correct syntax for accessing the session variable, which should be $_SESSION['variable_name'].
Verify that the variable you are trying to check is set in a previous request. Session variables persist across page loads, so they must be assigned in one script and checked in another.
Also check the case sensitivity of the variable name, as session variables are case-sensitive in PHP.

Common Mistake vs. Correct Approach

❌ Incorrect:

<?php
echo "<html>"; // Output before session_start() breaks the session
session_start();
if (isset($_SESSION['user'])) { ... }
?>

✅ Correct:

<?php
session_start(); // Must be the first PHP statement

// Set variable (e.g., after form submission)
// $_SESSION['user'] = 'admin';

// Check variable
if (isset($_SESSION['user'])) {
    echo "User is logged in.";
} else {
    echo "Session variable is not set.";
}
?>

Additional Troubleshooting: If the variable is set but isset() still returns false, check your server configuration. Values like session.gc_maxlifetime in php.ini or cookie settings (session.cookie_lifetime, session.cookie_secure) can cause sessions to expire or fail to send.

If you are still having issues, please provide more information about your code and the specific error message you are receiving.